AU595915B2 - Polymer-modified vinylized epoxy resins - Google Patents

Description

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AUSTRALIA

Patents Act 59 COMPLETE SPECIFICATION Cl as s Trt. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published:- Priority Related Art: 'M

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4. 1v1*1 APPLICANT'S REFERENCE: 32,619-F Name(s) of Applicant(s): The Dow Chemical Company Address(es) of Applicant(s): 2030 Dow Center, Abbott Road, Midland, Michigan 48640, UNITED STATES OF AMERICA.

This, du "xnent contain.,b I mThdfidnts roade under section) 49, an wa~aect for prnting I1"n .9 *4.

Address for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRAL,' Complete Specification fo~r the invention entitled: POLYMER-MODIFIED VINYLIZED EPOXY RESINS Our Ref 64168 POF Code: 1037/1037 The following statemient is a full description of this inventi!on, including the best method of performing it known to elplicant(s): 6003q/1 1i ;I i-l'"~l POLYMER-MODIFIED VINYLIZED EPOXY RESINS This invention relates to vinylized epoxy resins such as vinyl ester resins, and in particular, o vinylized epoxy resins which comprise polyrierizates contained therein.

Vinylized epoxy resins such as viuyl ester S«s. resins comprise a well known class of thermosettable polymers. Such vinyl ester resins possess excellent physical and chemical properties, and are partiou!arly useful as adhesives, in corrosion-resistant applications such as when formulated ai fiberreinforced plastic structures, as protective coatings for a variety of substrates, laminates, imolding compositions, encapsulants, etc. Typical formulations )mprising vinyl ester resins include plastic composite sheet molding compounds, resin transfer moldings and hand lay ups. For example, suoh resins are disolved in a solvent or reactive diluent such as styrene, applied to a substrate, and cured.

o 0 Vinyl ester resins are typically prepared by reacting an unsaturated monocarboxyllo acid with an 32,619-F -1 11:--

IV

r -2epoxy resin such that a resin containing the characteristic vinyl ester moiety is provided. The physical properties of the vinyl ester resins will typically depend upon factors such as the epoxy reactantu and the copolymerizable monomers which are employed, as well as the presence of various inert reinforcing agents such as glass fibers, carbon fibers, clays, etc.

Vinyl, ester resins having improved impact resistances are disclosed in U.S. Patent Nos. 3,674,893 and 3,892,819. These references disclose vinyl ester resins which are blended with unsaturated polydiene elastomers and are reacted or cured under conditions such that polydiene grafts are provided to the vinyl ester res.ns. While these references disclose composi- P tions which exhibit excellent impact and mechanical properties, the heat distortion temperatures of such compositions is not as high as would be desirable.

In view of the deficiencies of the prior art it would be highly desirable to prepare vinyl ester resin compositions capable of exhibiting good mechanical properties, having high heat distortion temperatures, 29 and providing cured products exhibiting reduced shrinkage and improved surface appearance.

The preser' invention is a vinylized epoxy resin, which vinylized epoxy resin comprises polymerizable ethylenic unsaturation and an in situ 'r polymerized polymer.

In another aspect the present invention is a dispersion which comprises an uncured vinylized epoxy resin prepared from an unoured epoxy resin as a continuous phase having dispersed therein an 32,61-F -3insoluble polymer and (ii) a dispersion stabilizer which is the polymerizate of at least one vinyl monomer and a vinyl:zed epoxy resin adduct derived from the reaction product of an unsaturated carboxylic acid, an unsaturated isocyanate or an alkenyl substituted phenol and a polyepoxide, said insoluble polymer having been polymerized in situ in the uncured epoxy resin and in the presence of the dispersion stabilizer, and the uncured epoxy resin subsequently vinylized by reacting Sthe uncured epoxy resin with an ethylenically unsaturated acid; the insoluble polymer dispersed phase further characterized in that it forms an insoluble polymer dispersion in the uncured epoxy and remains a stable dispersion in the vinylized epoxy resin at a .o temperature above 60 0

C.

,The dispersions of polymer and dispersion stabilizer in the polyepoxide continuous phase can be made by providing an adduct by reacting a minor amount of functionar monomer with a polyepoxide continuous phase providing a dispersion stabilizer by reacting the adduct with at least one monomer, and polymerizing said monomer(s) in the polyepoxide continuous phase and in the presence of said dispersion stabilizer; or providing an adduct by reacting a minor amount of functional monomer with a polyepoxide continuous phase providing a dispersion stabilizer by reacting the adduct with at least one monomer, while Qimultaneously polymerizing said monomer(s) in the polyepoxide continuous phase and in the presence of said dispersion stabilizer; and (II) vinylizing the polyepoxide.

As used herein the term "stable" is meant to refer to dispersions which remain substantially 32,619-, -3- 17- 17 .17i A r -4constant do not undergo flocculate or dissolve) under conditions of preparation as well as conditions of thermal cure. For example, the dispersion of polymer remains stable insoluble) under normal preparation, handling and processing curing) conditions by maintaining a substantially constant morphology size and distribution) in the continuous phase at some temperature normally some temperature above 60 0 C. Stable dispersions are, for example, those dispersions in which the polymer dispersed phase is insoluble in the continuous phase.

Insolubility can be qualitatively identified by a cloudiness of the composition to visible observation.

As used herein, the term "in situ polymerized polymer" is meant to refer to a polymer which is polymerized in said epoxy resin prior to the vinyliration of the epoxy resin. Such in situ polymerized polymers are referred to as polymerizates.

The compositions of this invention which can comprise vinyl ester groups can be described as polymer-modified vinyl ester resins. The compositions 25 are useful in a wide variety of high performance engineering thermoset applications in which good mechanical properties and high heat distortion temperatures are required. Such compositions can be cured to provide compositions useful in a wide variety of applications such'as fiber reinforced laminates; composites such as in fiberglass reinforced plastics and in glass reinforced plastic pipe; casting and molding resins; adhesives; enciapsulants; coatings such as radiation curable coatings; and the like.

32,619-F -4i The vinyl ester resin compositions of this invention are typically prepared by reacting an unsaturated carboxylic acid with an epoxy compound, which epoxy compound contains a polymerizate therein.

Also included as compositions of this invention are the types of compounds prepared by reacting a compound such as acrylamide with'an epoxy compound, which epoxy compound contains a polymerizate therein.

Epoxy compounds useful in this invention include a wide variety of epoxy compounds. Typically, the epoxy compounds are epoxy resins which are also referred to as polyepoxides. Polyepoxides useful herein can be monomeric the diglycidyl ether of bisphenol advanced higher molecular weight resins, trr: or polymerized unsaturated monoepoxides glycidyl acrylates, glycidyl methacrylate, allyl glycidyl ether, etc.) to homopolymers or copolymers. Most desirably,, epoxy compounds contain, on the average, at least one pendant or terminal 1,2-epoxy group vicinal epoxy group) per Tiolecule.

Examples of useful polyepoxides include the polyglycidyl ethers of both polyhydric alcohols and polyhydric phenols; polyglycidyl amines, polyglyoidyl amides, polyglycidyl imides, polyglycidyl hydantoins, polyglycidyl thioethers, epoxidized fatty acids or drying oils, epoxidized polyolefins, epoxidized diunsaturated acid esters, epoxidized unsaturated polyesters, and mixtures thereof. Numerous polyepoxides prepared from polyhydric phenols include those which are disclosed, for example, in U.S. Patent No. 4,431,782. Polyepoxides can be'prepared from mono-, di- and tri-hydric phenols, and can include the novolac resins. Polyepoxides ca~t include the 32,619-F .i

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-6epoxidized cycloolefins; as well as the polymeric polyepoxides which are polymers and copolymers of glycidyl acrylate, glycidyl methacrylate and allylglycidyl ether. Suitable'polyepoxides are disclosed in U.S. Patent Nos. 3,804,735; 3,892,819; 3,948,698; 4,014,771 and 4,119,609; and Lee and Neville, Handbook of Epoxy Resins, Chapter 2, McGraw Hill,. New York (1967).

While the invention is applicable to polyepoxides, generally preferred polyepoxides are glycidyl polyethers of polyhydric alcohols or polyhydric phenols having weights per epoxide group of 150 to 2,000.

These polyepoxides are usually made by reacting at 15 least two moles of an epihalohydrin or glycerol Sdihalohydrin with one mole of the polyhydric alcohol or polyhydric phenol, and a sufficient amount of a caustic alkali to combine with the halogen of the halohydrin.

The products are characterized by the presence of more than one epoxide group, a 1,2-epoxy equivalency greater than one.

The polyepoxide may also include a minor amount of a monoepoxide, such as butyl glycidyl ether, phenyl glycidyl ether, or cresyl glycidyl ether, as a reactive diluent. Such reactive diluents are commonly added to polyepoxide formulations to reduce the working viscosity thereof, and to give better wetting to the formulation. As is known in the art, a monoepoxide S affects the stoichiometry of the polyepoxide formulation and adjustments are made in the amount of curing agent and other parameters to reflect that change.

Polymerizates which are contained in the epoxy compound are typiolly organic polymers which are most 32,619-F -6r -7desirably polymerizates of at least one ethylenically unsaturated monomer. Vinyl monomers useful herein are those which polymerize in situ in the polyepoxy continuous phase and provide polymers which form stable dispersions in the continuous phase. Combinations of monomers can be employed and polymerized in order to provide a stable dispersion in the epoxy resin as defined hereinbefore. Examples of vinyl monomers which may be employed include butadiene, isoprene, 1,4- 10 pentadiene, 1,6-hexadiene, 1,7-octadiene, styrene, amethylstyrene, methylstyrene, 2,4-dimethylstyrene, ethyistyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, and the like, substituted styrenes such as chlorostyretie, S 2,5-dichlorostyrene, bromostyrene, fluorostyrene, S trifluoro-methylstyrene, iodostyrene, cyanostyrene, nitrostyrene, N,N-dimethylaminostyrene, acetoxylstyrene, methyl-4-vinyl-benzoate, phenoxystyrene, p-vinyl diphenyl sulfide, p-vinylphenyl phenyl oxide, and the like; substituted acrylic monomers such as acrylonitrile, methyl methacrylate, butyl acrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropyl methacrylate, octyl 25 methacrylate, methacrylonitrile, methyl achloroacrylate, ethyl a-ethoxyacrylate, methyl aacetaminoacrylate, butyl acrylate, ethyl acrylate, 2ethylhexylacrylate, phenyl acrylate, phenyl 30 methacrylate, a-chloroacrylonittile, NN-dimethylacrylamidc, N,N-dibenzylacrylamide, N-butylacrylamide, methacrylyl formamide, and the like; the vinyl esters, vinyl ethers, vinyl ketones, etc.,.suich as vinyl acetate, vinyl chloroacetate, vinyl butyrate, isopropenyl acetate, vinyl formate, vinyl methoxy acetdte, vinyl benzoato, vinyl iodide, vinyl toluene, 32,619-F -7vinyl naphthalene, vinyl bromide, vinyl chloride, vinyl fluoride, vinylidene bromide, vinyl.idene chloride, 1chloro-l-fluoro-ethylene, vinylidene fluoride, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ethers, vinyl butyl ethers, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-methoxyethyl ether, methoxybutadiene, vinyl 2-butoxyethyl ether, 3,4dihydro-1,2-pyran, 2-butoxy,-2'-vinyloxy diethyl ether, vinyl 2-ethylmercaptoethyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl phosphonates such as bis(pchloroethyl)vinyl phosphonate, vinyl phenyl ketone, vinyl ethyl sulfide, vinyl ethyl sulfone, N-methyl-Nvinyl acetamide, N-vinyl-pyrrolidone, vinyl imidazole, divinyl sulfide, divinyl sulfoxide, divinyl sulfone, S sodium vinyl sulfonate, methyl vinyl sulfonate, N-vinyl pyrrole, and the like; dimethyl fumarate, dimethyl maleate, monomethyl itaconate, t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, allyl alcohol, dichlorobutadiene, vinyl pyridine and the like. Any of the known polymerizable monomers can be used and the compounds listed above are illustrative and nct restrictive of the monomers suitable for use in this invention.

Preferably, the monomer which is employed forms a soft polymer measured as a glass transition ttmperature below use temperature. 'Representative monomers are the alkyX esters of acrylic and methacrylic acids, preferably wherein the alkyl group contains at least 4 carbon atoms, more preferably greater than 4 carbon atoms, and most preferably greater than 4 to 24 carbon atoms. A monomer such as 2-ethylhexyl acrylate is preferred. Other representative moromers are the dienes such as 32,619-F -8- -i -9butadiene and isoprene. Copolymers of such monomers with other comonomers can also be used. For example, styrene and butadiene form a well-known class of elastomers. Most preferred are the monomers forming elastomers.

Although monomers forming polymers having high softening temperatures can be used, the polymers have less beneficial influence on the toughness of the cured dispersions. Such polymers can be employed as might be desired, for example, as pigments, fillers, low profile agents for providing reduced shrinkage and improved surface appearance, etc. Generally, it is desirable to employ a stabilizer. However, compositions within the present invention can be formed with hard polymers o having a glass transition temperature or crystalline 9 melting point above the polymerization temperature of oo the polymer and cure temperature of the polyepoxide 20 without the presence of a stabilizer, e.g., 0. polyacrylonitrile.

A functional monomer having a reactive group in addition to a polymerizable vinyl functionality can be 25 incorporated in a small amount in the monomer mixture which polymerizes to forn' the dispersed phase.

Illustrative of functional monomers are acrylic acid, 0* methacrylic acid, crotonic acid, itaconic acid, 2hydroxyethyl or propylaorylate, 2-hydroxyethyl methacrylate, t-butyl-aminoethyl methacrylate, isocyanatoethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, glycol, monoesters of itaconic acid, methyl monoester of itaconic acid, acrylamide or substituted acrylamides, allyl alcohol, maleic acid, fumaric acid, isopropenyl phenol, and the like. Such monomers can provide sites for subsequent crosslinking 32,619-F -9or for bonding to the polyepoxide continuous phase matrix.

In addition, monomers containing more than one vinyl group can be used at low levels to increase the molecular weight of the dispersed phase. Examples of such comonomers are the polyvinyl monomers, such as divinylbenzene, allyl methacrylate, ethylene glycol dimethacrylate, and the like.

P Ecby 1 vinyl polymerization is induced and maintained by conventional free radical catalysts and elevated temperatures. The concentration of the catalyst.VarCsfrom 0.001 to 10 percentc preferably.

from 0.2 to 1.0 percent; however, any effective catalytic amount is satisfactory. Illustrative catalysts are the well-known free radical type of vinyl polymerization catalysts, for example, the peroxides, persulfates, perborates, percarbonates, azo compounds, etc., including hydrogen peroxide, dibenzoyl peroxide, acetyl peroxide, benzoyl hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, butyryl peroxide, diisopropylbenzene hydroperoxide, Scumene hydroperoxide, paramenthane hydroperoxide, diacetyl peroxide, di-alpha-cumyl peroxide, dipropyl peroxide, diisopropyl peroxide, isopropyl-t-butyl peroxide, butyl-t-butyl peroxide, dilauroyl peroxide, difuroyl peroxide, ditriphenylriet'hyl peroxide, bis(pmethoxybenzoyl)peroxide, p-monome-thoxybenzoyl peroxide, rubrene peroxide, ascaridol, t-butyl peroxybenzoate, diethyl peroxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide, cyolohexyl hydroperoxide, trans-Decalin hydroperoxide, alpha-methylbenzyl hydroperoxide, 32,619-F Li -11alpha-methyl-alpha-ethyl benzyl hydroperoxide, Tetralin hydroperoxide, triphenylmethyl hydroperoxide, diphenylmethyl hydroperoxide, alpha,alpha'-azo-2-methyl butyronitrile,. alpha,alpha' -2-methyl heptonitrile, 1,1'-azo-1-cycloexane carbonitrile, dimethyl, alpha,-alpha'-azo-isobutyrate, 4,4'-azo-4cyanopentanoic acid,. azobisisobutyronitrile, persuccinic acid, diisopropyl peroxy dicarbonate, and the like; a mixture of catalysts can also-be used.

The vinyl polymerization can also be carried out with an inert organic solvent present.

Illustrative thereof are toluene, benzene, o-xylene, acetonitrile, ethyl acetate, hexane, heptane, dicyolohexane, dioxane, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, halogenated solvents and the like, including those known in the art as being 9uitable solvents for the polymerization of vinyl monomers. The only requirement in the aselectLion of the inert solvent is that it does not substantially interfere with the monomer's polymerization reaction.

Any solvent, if used, can be removed before further conversion of the polymerization product to a vinyl ester compound. However, it is preferable to remove the solvent before dilution with a reactive diluent.

The vinyl polymerization system can also contqin small amounts of from 0.1 to 2 percent by weight of a chain transfer agent based on the weight of vinyl monomer in the dispersed phase. Alkyl mercaptans having from one to twenty carbon atoms in the alkyl chain may be employed in the present invention. Representative meroaptans include ethyl mercaptan, propyl mercaptan, butyl mercaptan, hex/yl meaptan, octyl mercaptan, decyl mercaptan, dodecyl meroaptan, tetradecy mercaptan, cetyl mercaptan, stearyl mercaptan.

32, 619-F -11- :'ICYII-i C- l~ o 12- Other chain transfer agents such as disulfides and halogenated compounds, especially brominated compounds, can be used.

Dispersion stabilizers are employed in the process of this invention in order to prepare a dispersion more easily and also to provide dispersions having superior stability. A dispersion stabilizer is any molecule which contains at least two different segments, blocks or functionalities, one of which is compatible with the polyepoxide and one of which is compatible with the polymer particles of the dispersed phase. See, for example, Dispersion Polymerization in Organic Media, edited by K. E. J, Barrett, John Wiley and Sons, London (1975).

Reactive functional monomers useful in preparing dispersion stabilizers of this invention can be described as those monomers having a functionality capable of undergbing a polymerization reaction with the monomers forming the dispersed phase a vinyl functionality) and a functionality capable of reacting or coupling with a reactive moiety of an epoxy compound an epoxy functionality), The reaott P:; of a reactive functional monomer anat an i form a new product having vinyl unsat uatiQn bE called a Vinylized adduct. Vinyliied adduUi typically prepared by reacting ,ii oxirane mtolety of a polyepoxide with an e~hylenically unsaturated functional monomer such as those described hereinbefore. Reactivity of monomers, procAss conditions for reaction and other reacticn parameters are dislosed ~n Lee and Neville, Handbook ,of Ekgg Resins, McGraw Hill, New York (1967) at Appeodix "1 and the bibliography in Chapter 5, pago- V0 32,619-F -12-

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-13- Catalysts useful in preparing reactive functional monomers from, for example, polyepoxides and unsaturated carboxylic acids include the ethyl triphenyl phosphonium acetate, acetic acid complex and other onium compounds; tertiary amines such as tris(dimethylaminoethyl) phenol; triphenyl phosphine; metal salts such as chromium chloride and chromium acetate; and other catalysts which catalyze the epoxy/carboxy reaction. If desired, it is possible to icorporate a polymerization inhibitor into the reaction mixture in order to prevent premature vinyl polymerization of the ethylenically unsaturated moieties prior to the completion of the epoxy/carboxy reaction. Examples of such inhibitors include 2,6-ditertiary-butyl-4-methylphenol, p-methoxyphenol, hydroquinone and tetrahydrothizine. Such inhibitors can be additionally employed for improved storage of the reactive functional monomer.

The dispersion stabilizer can be prepared using a Variety of techniques. For example, the dispersion stabilizer can be prepared in situ early in the preparation of the dispersion by reacting a functional 25 monomer acrylic acid) with the'epoxy compound in t.w the presence of a suitable catalyst. The resulting epoxy compound having reactive functional groups ethylenically unsaturated moieties) can be further reacted with the other monomers which polymerize to form the dispersed phase. Alternatively, S for example, the d spersion stabilizer can be prepared separately and added to the epoxy compound before or during addition and polymerization of the monomers which polymeriza to form the dispersed phase.

32,619-F -13-

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4 -27i U- S -14- The process of this invention in one aspect provides a means for the skilled artisan to prepare stable dispersions of a polymer in a polyepoxide continuous phase, in which the polymers are dispersed as particles which are formed before curing. The polymers which form the dispersed phase can comprise the poly lerfzation product of one or more monomers (e.go, form a copolymer). The polymerization reaction can be a step reaction such as in the preparation of condensation polymers, or an addition polymerization such as in the polymerization of ethylenically unsaturated monomers. The addition polymerization can be cationic, anionic or coordination polymerization; or free-radical chain addition. Generally preferred is the free-radical chain addition. Most preferred is the free-radical polymerization of one or more ,U ethylenically unsaturated monomers.

Stable dispersions of polymers in the polyepoxide are those dispersrons which remain stable at a temperature preferably above 60'C, preferably above 0 C. For example, the polymer which forms the stable dispersed phase is one which is insoluble in the polyepoxide continuous phase at some temperature above 600C, preferably at some temperature abova 900C. Thus, for purposes of this invention the term "good stability" is referring to the dispersions of this Sinvention can mean that the particles do not I 30 coagulate or coalesce to an appreciable degree prior to use or during the curing process; the particles have a controlled particle size; the dispersions can be stiored for reasonable periods without premature curing; and the particles maintain a size and 32,619-F -14- S dispersion distribution which remains substantially unchanged during storing and processing.

Because this invention in one aspect concerns the use of stable dispersions of polymers in a polyepoxide continuous phase, it is understood that the stability of the dispersion depends upon the appropriate combination of polymeri-ate and epoxy resin. If the polymerization product of a particular monomer or monomers which form the desired dispersed phase in the polyepoxide forms an unstable dispersion it is possible that the desired results can be obtained Sn with the same monomer or monomers in a different 1 polyepoxide. The stability can be improved in order to 15 provide a dispersion which remains stable in the 4 polyepoxide as per the definition of this invention by employing a particular ilyepoxide, a particular dispersed phase polymer, 'ombination of a particular polyepoxide and a particular dispersed phase polymer, a dispersion stabilizer, or"a change in the polymerization process.

Compositions of this invention are prepared by reacting the epoxy compound containing the polymerizate with a functional monomer in order to provide a reaction product of the epoxy resin with the functional monomer such that a compound containing vinyl unsaturation is obtained.

In order to form the vinyl ester resins, the polyepoxides containing the polymerizate. are typically reacted with ethylonically unsaturated acids. The unsaturated acids employed hereir in forming the vinyl ester group are protonio acids preferably having a dissociation constant of at least 1 x 10"7, most 32,619-F S-16preferably at least 1 x 10 5 Such acids are normally organic carboxylic acids and are more preferably monocar-boxylic acids. Suaabia acids include, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnanic acid, longer chain acids such as oleic acid, linoleic acid, tall oil acid and dimer acids, and the half esters of hydroxy alkyl acrylates and methacrylates formed, for example, by reacting 2hydroxyethyl acrylate with phthalic anhydride," maleic anhydride, succinic anhydride and the like. Acrylic acid and methacrylic acid are the most preferred Smonocarboxylic acids. Mixtures of saturated acids and the acids bearing polymerizable vinyl groups can also 15 be used, for example, as a means of limiting the vinyl functicnality of the product. Mixtures of saturated acids and the ac,;ds bearing polymerizable vinyl groups can also be used. Mixtures of this type represent a means of limiting the vinyl functionality of the product, etc.

T'he dispersion is converted to, a vinyl ester resin composition by contacting the modified polyepoxide with the unsaturated acid and subjecting the mixture to conditions such that vinyl ester functionalitie are formed.

y the equivalent amount of unsaturated carboxylic acid per Opoxy group ranges from 0.1 to 1.2 oie preferably from 0.25 to 1.1, most preferably 1.

Numerous factors affect the stability or insolubility of the dispersed polymer in the vinyl ester resir continuous phase. For example, vinyl ester resins having greater viscosities provide greater stability to the polymers of the dispersed phase.

32,619-F -16- 4, 1 -17- Dispersed polymer particles of smaller particle size generally have greater stability than larger size particles. A small difference in density between the dispersed and continuous phases generally provides a composition having greater dispersion stability than a composition having a large difference in density between the components of the aforementioned phases.

Particles having less tendency to agglomerate provide compositions which 'have greater stability than those compositions which contain components which have a greater tendency to agglomerate. Thus, by altering the ,o°o types of components which are employed in preparing the composition of this invention, it is possible to control factors such as the coagulation or coalescence 15 of the dispersed phase in the continuous phase. It is understood that the presence of a dispersion stabilizer or the absence of undesirable flocculants in the composition can also control the amount of undesirable coagulation or coalescence of the dispersed phase in the continuous phase which occurs.

The polymerizate which forms the dispersed phase can be in an amount of from 5 to 70 volume percent, preferably 5 to 50 percent of the total dispersion. The optimum concentration of vinyl polymer phase can and will be varied depending upon the materials employed and the end use that is envisaged.

The dispersions are usually made at a solids level at which the dispersions are to be used. However, it is possible to prepare higher solids dispersions and dilute to the final solids level.

The properties of the dispersion are influenoed by a variety of factors including the identity of the components, the particle size and concentration of 32,619-F -17i: -18the dispersed phase, the hardness or softness of the particles of the disperse phase, the concentration of the dispersion stabilizer and many other factors. For many applications it is most desirable to employ a dispersed phase polymer having a solution temperature above the polymerization temperature of said polymer.

For most practical applications, the stability of the dispersion and the property enhancement due tothe disperse phase polymerizate will be optimized with particles that are less than some critical particle size which is 20 microns.

The aforementioned vinyl ester resins can be 15 copolymerized with vinyl-functional chain extending S monomers which act as flexibilizers or modifiers to the vinyl ester resin polymer. Suitable monomers include vinyl aromatic compounds such as styrene, vinyltoluene, divinylbenzene, t-butylstyrene, chlorostyrenes, vinylbenzylcloride, and the lfke; esters of acrylic acid or methanrylic acid such as 2-ethylhexyl acrylate, butyl acrylate, trimethylolpropane tnimethacrylate, 1,3-butylene glycol dimethacrylate, methyl methacrylate, ethyl acry1te, hydroxy alkyl acrylates and methacrylates and th diallyl maleate, dimetrallyl fumarate and nitrogen-containing monomers such as t-butylaminoethyl methacrylate, N,N'-dimethylaminoethyl acrylate, N,Ndiethylaminoethyl methacrylate, N,N'-dimethylaminoethyl methacrylate, N-vinylpyrrolidone, 2-Nmorpholinoethyl acrylate; diallylpthalate; and mixtures thereof. Essentially any other monomer which is capable of copolyerizing with the vinyl ester resin can be used.

32,619-F -18- 1 -19- It is understood that the vinyl-functional chain extending monomers are optionally employed, and when employed are so used in amounts to achieve the desired polymeric properties. The vinyl ester resin generally comprises from 20 to 100, preferably from to 100, weight percent of the vinyl ester resin polymer, while the vinyl-functional chain extending monomer comprises from 0 to 80, preferably from 0 to weight percent of said vinyl ester resin polymer.

The dispersions are solidified by curing the S vinyl ester resin. In the curing of vinyl ester resin s the choice of curing agent can influence the cure rate, the exotherm and resultant properties of the finished The curing agents or initiators most commonly used to effect crosslinking or cure of vinyl ester resins are organic peroxides or hydroperoxides.

Decomposition of these initiators can be effected by heat or by the use of accelerators or promoters which cause a more rapid decomposition of the initiator at a given temperature. The accelerators most commonly employed are the tertiary amines and the metalic soaps, such as cobalt or manganese octoate or naphthenate.

See, Paul F. Bruins, ed., "Unsaturated Polyester Technology", Gordon and Breach Science Publishers, New York, 1976, p. 329.

The following examples are given to illustrate the invention.

Example 1 A vinyl polymer/epoxy resin polymerizate was prepared as follows: 1,000 g of a diglycidyl ether of bisphenol-A (a liquid epoxy resin sold commercially by 32,619-F -19- 4 The Dow Chemical Company as 383 epoxy resin, having an epoxy equivalent weight of from 178 to 186 and a viscosity at 25°C of between 9,000 and 11,500 centipoise (9 and 11.5 Pa.s)) was charged into a fiveneck, two-liter round bottom flask equipped with a dual syringe pump for vinyl monomer addition, means for initiator addition, stirring means, condenser, thermometer and nitrogen/air sparge. The epoxy resin was heated to 80°C with stirring at which point 8 g of methaorylic acid was added (continuously), followed by the addition of 0.01 g hydroquinone (inhibitor) and with 0.25 g of a 70 percent solution of ethyltriphenyl phosphonium acetate-acetic acid complex in methanol.

t. 15 This mixture was heated to 115°C with air sparge over a tl 15 minute period and held at this temperature for minutes. To the resulting precursor mixture was added a monomer mixture of 112.5 g 2-ethylhexyl acrylate and 37.5 g glycidyl methacrylate over a 35 minute period with nitrogen sparge. A further monomer mixture of g 2-ethylhexylacrylate and 7 g glycidyl methacrylate was added over a 25.minute period. Over the one hour S period that the two monomer mixtures were added 2.8 g S of tertiarybutyl perbenzoate catalyst was added to the precursor mixture. The total mixture was reacted at S 115°C for an additional four hours, and the mixture was further heated to 145°C for 15 minutes. The resulting product was a viscous, white dispersion.

The product was treated as follows: The product (48.33 percent of the reactant mixture) was heated to 90 0 C in the previously described flask with agitation under air sparge. To the flask was charged 209 ppm hydroquinone, methacrylic acid (16.52 percent 6f reactant mixture), and a 0.33 percent active 32,619-F -21hydrated chromium chloride catalyst formulation (0.06 percent of reactant mixture). The mixture was heated to 115°C. The mixture was tested to determine the amount of free acid present. At 1 to 1.2 percent acid, oxalic acid (0.03 percent of reactant mixture) was charged to the mixture. After 5 minutes, to the mixture was charged styrene (17.5 percent of reactant mixture),. When the mixture cooled to 90°C or less, to the mixture was charged 4-chloro-2-nitrophenol (inhibitor) (0.01 percent of reactant mixture), phenothiazine (inhibitor) (0.02 percent of reactant mixture) and styrene (17.5 percent of reactant mixture) as taught in U.S. Patent No. 4,407,991 and 4,413,105.

a. The mixture was cooled with air sparge to less than 15 and the vinyl ester resin product was removed from the t" reactor. The product contains 9.67 percent rubber polymerized therein.

Castings were prepared by curing the resin product with 0.3 percent of cobalt naphthenate solution (6 percent active cobalt in a mineral spirits solution) and 1.22 percent of methyl ethyl ketone peroxide solution (50 percent methylethyl ketone peroxide in dimethyl phthalate). The resin was cured at ambient temperature for about 16 hours and post-cured for 2 hours at 311 0 F (1550C). This sample was designated as Sample No. 1.

In a similar manner were prepared castings of vinyl ester resin products containing 40 percent styrene, 45 percent styrene and 30 percent styrene polymerized therein. These samples were designated as Sample Nos. 2, 3 and 4 respectively. For comparison purposes were prepared vinyl ester resin products containing 35, 40, 45 and 30 percent styrene, but 32,619-F -21- Ii6ia- -22prepared from the epoxy resin and not from the rubbermodified epoxy resin. These samples were &.--signated as Sample Nos. C-1, C-27 C-3 and C-4i respectively.

Data concz ,,Ing the physical properties of the various samples are presented in Table 1.

0 0 3' 32,6 19-F -2 -22- 4 44., 004 0 a 3 4 0 44 a 40 fr a a a a TABLE I Percent~l) Sample Rubber Tensile (9) (psi) (MPa) 3 4 C-1 G-2 C-3* c-4* 9.67 9,730(67) 8.93 9,8901(I68) 8.18 9,440(65) 10-33 8,558(59) 8,558(59) 7,030(48.5) 9,080(62.6) 7,520(52) Tensile( 3 Modulus 3. 4C(2344) 3 .33 (2296) 3.37(2323) 3. 69(2544) 4. 11(2834) 3. 91(2696) 3.95(2723) 4.99(344G) Percent( 4 Elongation 4.47 5.20 4.46 4.07 1.87 2.70 31. 95 (2723 4.99(3440) Flexural (5) (psi) (Ma) Flexural (6) Modulus 17,76-00122) 20,7900143) 181840(130) 12,435(86) 17,568(121) 22,800(157) 2.14 2.55 4.58(3 158) 5.57(3840) 4.13(2847) 3.52(2427) 5.66(3902) 5.6 1(3868).

5.48(3778) 5.63(3882) HDT (7) (OF) (00) 206(97) 212(100) 208(98) 211(99)F 261(127) 263(028) 257(125) 2650 29) -Barcol( 8 *t an example of the invention.

,,)Percent Rubber is based on the weight of' vinyl ester resin plus styrene.

See ASTM D-638-82A ()SeASTM.D-638-82A,. Reported in psi x 105 M~) Se.ASTM D-638-82.

MseASTM D-790-81.

6 )See ASTM D-790-81. Reported in psi x 105 (MWa).

(?See ASTM D-648-82.

8 )See ASTM D-2583-81 1 The data in Table I indicate that improved elongation is obtained by the samples of this invention, which samples containing the dispersed acrylic elastomer.

Example 2 A vinyl polymer/epoxy resin polymerizate was prepared as follows: 6,218,2 g of the epaxy resin described in Example 1 was charged into a system as described in Example 1, The resin was heated to 80 C and 48.32 g of methacrylic acid and 3.11 g of ethyl Sr 'Lriphenyl phosphonium acetate-acetic acid complex (catalyst) were charged into the system. The mixture 15 was heated to 115C0 for 30 minutes followed by heating t to 1200C with nitrogen sparge. A monomer mixture containing 1,557 g 2-ethylhexyl acrylate and 149.3 g methacrylio acid was added to the flask containing the resin over a 1 hour period. Simultaneously was added 2C an initiator solutiJn confalning 7.79 azobisisobutyronitrile in 194.6 g toluene, but over a 2 hour period, Following addition of monomer and initiator, the system was subjected to reaction conditions for an additional 30 minutes. Following completion of the reaction, the toluene was stripped under vacuum conditions. The product was a viscous, white dispersion.

In a manner described in Example 1 was prepared a vinyl ester resin and vinyl ester resin products by polymerizing styrene therewith. Sample Nos. 5 and 6 contain vinyl ester resin polymerized with 40 percent styrene and 45 percent styrene, respectively.

32,619-F -24- K- Data concerning the physical properties of the various samples are presented in Table II.

0 32, E6 1 9-F 1-'25-

J

41 y I. 0~0 S OS S S 00 04 4 0 0 TABLE II SamplePecn" Rubber TensileC 2 (psi) (MPa) 'Tensile( 3 Percent('4) Flexural(5) Flexural( 6

HDTM

7 Modulus _Elongation (psi) (MPa) Modulus 0 F) (oC) Barool( 8 8.61 9, 152(63) 4.42(304T) 2.54 20,59804M2) 5.26(3267) 233(012) 6 7.90 For Footnotes (1) 9,337(64) through 4.42(30147) 2.55 see corresponding Foot-notes at Table I~.

218(003) -27- Example 3 A vinyl polymer/epoxy resin polymerizga' was prepared as follows: 1,000 g of a diglycidyl ether of a novolac of phenol and formaldehyde having an average number of phenols and thus an oxirane functionality of 3.6; an epoxide equivalent weight of from 175 to 182 and a viscosity at 25°C of between 30,000 and 90,000 centiposes (30 and 90 Pa.s), and sold commercially as D.E.N.®438 epoxy novolac by The Dow Chemical Company, was charged into a system as described in Example 1.

The resin was heated to 80°C with stirring and 8 g of methacrylic acid followed by 0.01 g of hydroquirone and SF t 0.25 g of ethyl triphenyl phosphoniuim acetate-acetic acid complex were charged into the( system. The mixture was heated to 115°C with air sparge over a 15 minute period and held at this temperature for 30 minutes.

The mixture was heated to 130°C with a nitrogen sparge and a mixture of 150 g 2-ethylhexyl acrylate and 24.2 g glyoidyl methacrylate was added thereto over a Sminute period. To the mixture was then added a mixture of 100 g 2-ethylhexyl acrylate, 161.3 g glycidyl methacrylate and 1.25 g trimethyolpropane triacrylate over a 25 minute period. Simultaneously to the additions of the monomer mixtures was added 4.4 g of tertiary butyl peroxybenzoate catalyst but over a 2 hour period. The mixture was then reacted for an additional hour. The final product was a viscous, white dispersion.

The product was treated as follows: The product (51.37 percent of the reactant mixture) was heated to 90°C in the previously described flask with agitation under air sparge. To the mixture was added hydroquinone (0.03 percent of the reactant mixture), 32,619-F -27t -28methacrylic acid (18.46 percent of the reactant mixture) and 0.33 percent active hydrated chromium chloride catalyst formulation (0.06 percent of reactant mixture). The mixture was heated to 115 0 C. The mixture was tested to determine the amount of free acid present. At 1 ,to 1.2 percent acid 'lic acid (0.02 percent of reactant mixture) was charged to the mixture. After 5 minutes, to the mixture was charged styrene (15 percent of reactant mixture). When the 1 mixture cooled to below 90 0 C, to the mixture was charged styrene (15 percent of reactant mixture) and Sphenothiazine (0.03 percent of reactant mixture). The mixture was cooled to less than 40 0 C with air sparge "15 before removing the vinyl ester resin from the reactor.

The product contained 10.27 percent rubber polymerized S thorein. Castings were prepared by curing the product as described in Example 1. This sample is designated as Sample No. 7.

In a similar manner were prepared castings of a vinyl ester resin product containing 35 percent styrene polymerized therein. The sample was designated as Sample No. 8. For comparison purposes were prepared vinyl ester resin products containing 30 and 36 percent styrene, but prepared from the epoxy resin and not from the rubber-modified epoxy resin. These samples were designated as Sample Nos. C-5 and C-6. respectively.

Data concerning the physical properties of the various samples are presented in Table No. III.

32,619-F -28-

S."

*00 4 4 I 4 9 S.0 4 0 9 4 #4 4 9 TABLE ill Sample Percent (1) Rubber Tensile( 2 (psi) (MPa) Tensile( 3 Modulus Percent('4) Flexural(5) Flexural( 6 HDT(7) Elongation (rsi) (MPa) Modulus 0 F) 0

C)

Barcol( 8 7 10.27 8,101(56) 3.71(2558) 3.31 15,670(108) 4.61(3178) 2680131) 8 9.54 8,161(56) 4.03(,2779) 2.98 16,299(112) 4.59(3165) 266(130) 6,121(142) 4.10(2827) 1.66 11,2514(78) 5.32(3668) 320(160) C-6 101060(69) 5.93(4089) 2.25 19,865(137) 6.156~240) 291044i~) *wan example of the invention For Footnotes through see corresponding Footnotes at Table 1.

The data in Table III indicate that improved elongation is exhibited by the sample of this invention while high heat distortion temperatures are maintained.

Example 4 A dispersion of poly-2-ethylhexyl acrylate in the epoxy resin described in Example 2 was prepared as described in Example 2. The product contained 18 percent rubber. This product (30.86 percent of the reaction mixture) was charged with bisphenol-A (7.13 percent of reaction mixture) in the system described in Example 1. This mixture was heated to 90°C, agitated, sparged with nitrogen and charged with tetrabutyl 15 phosphonium acetate-acetic acid complex (0.03 percent of reaction mixture). The mixture was heated to 150°C and allowed to react for 1.5 hours after the temperature of 150°C was reached. The mixture was cooled to 120°C and allowed to react for an additional 2 hour. Under air sparge was charged hydroquinone, methacrylic acid and 0.33 percent active hydrated chromium chloride formulation (0.03, 15.85 and 0.07 percent of the reaction mixture, respectively) to the mixture. The mixture was heated to 115°C. When the free acid content of the mixture was 1-1.2 percent, the heating of the mixture was discontinued. To the mixture was charged oxalic acid (0.02 percent of reaction mixture). After 5 minutes styrene (15 percent of reaction mixture) was charged to the mixture. When the mixture cooled to less.than 900C, 4-chloro-2nitrophenol, phenothiazine, and styrene (0.01, 0.015 and 15 percent of the reaction mixture, respectively) were charged to the mixture. The mixture was cooled to less than 40°C with air sparge before removing the vinyl ester resin from the reactor. Castings were prepared 32,619-F _-7 -31as described in Example 1. The sample was designated as Sample No. 9.

In a similar manner was prepared a casting of a vinyl ester resin product containing 35 percent styrene polymerized therein. This sample was designated as Sample No. For comparison purposes were prepared vinyl ester resin products containing 30 and 35 percent styrene polymerized therein, but -prepared from the epoxy resin and not from the rubber-modified epoxy 0 resin. Thede samples were designated as Sample Nos. C- 7 and C-8, respectively.

For comparison purposes were prepared vinyl ester resin products containing 30 and 35 percent styrene polymerized therein, and amounts of carboxyterminated butadiene/acrylonitrile polymers therein.

These samples were designated as Sample Nos. C-9 and Crespectively.

Data concerning the physical properties of the various samples are presented in Table IV.

32,619-F -31u

L

"fr *0 bas 00 S 0 00 0 0 0 0 0 9 0 0 TABLE IV sample Perceit.(1) Tens ile( 2 (psi) (MPa) Tensile( 3 PercentV4) Flexural( 5 Modulus __Elongation (Dsi)(MPa) Flexural( 6 Modulus 9 6.17 9,171(63) 4.09(2820) 2.87 17,41030120) 4.56(3144) 5.73 11,066C76) 4.31(2972) 4.146 19,735(136) 4.77(3289) C-7~ 8,2M..'57) 4.34(2992) 2-19 13,281(92) 5.63(3882) 9,1461(65) 5.33(3675) 2.15 13,372(92f) 5.80(3999) C-9 7.65 11,050(76) 4.33(2985) 3.94 219;624(1149) 5.39(3716) 7.06 11,386(78) 4.140(30341) 4.88 .209146f(1141) 5.3903716) *Not an example of~ the invention For Footnotes through see corresponding Footnotes at Table I.

HDT 7 (OF) 0

C)

2144(117) 2146(119) 2541(123) 255(124) 207(97) 208(98).

I

II

-33- The data in Table IV indicate that the sample of this invention exhibits a higher heat distortion temperature over a sample containing a carboxyterminated butadiene acrylonitrile polymer.

Example A vinyl polymer/epoxy resin polymerizate was prepared as fol'lows: 1,600 g of a triglycidy'l ether of tri(p-hydroxy) phenyl methane (a semi-solid epoxy resin sold commercially by The Dow Chemical Company as XD- 7342.00 epoxy resin) was charged into a three-liter, o o three-necked flask equipped with addition funnel, t:o, stirrer, thermocouple, condenser and nitrogen/air sparge. The epoxy resin was heated to 100°C with stirring at which point 15 g methacrylic acid was added (continuously), followed by the addition of 1 g of a percent solution of ethyltriphenyl phosphonium acetateacetic acid complex in methanol. The mixture was held at 100 0 C for an additionar hour and then heated to 150°C, At this time, a solution of 500 g 2-ethylhexyl acrylate and 5 g of a commercially available 2tertiary-butylazo-2-cyanobutane initiator was added over a one hour period. After heating for an additional 30 minutes at 150 0 C, the volatiles were removed under vacuum (at less than 1 mm Hg). The resulting product was a yellow, semi-solid dispersion having 18 percent solids and 20-45 percent epoxide.

The product was treated as follows: 'The.

product (50.00 percent of the reactant mixture) was heated to 90°C in the previously described flask of Example 1 with agitation under a nitrogen sparge. To the flask was added 0.0714 percent of a 70 percent solution of ethyltriphenyl phosphonium acetate-acetic 32,619-F -33- -i, 1 acid complex in methanol (0.04 percent of the reactant mixture) and the temperature was raised to 120 0 C and held for one hour. Then 400 ppm hydroquinone (0.03 percent of the reactant mixture) and methacrylic acid (19.82 percent of the reactant mixture and 97 percent stoichiometry based on epoxy content) were added with mixing. Under an air sparge, 33 percent active hydrated chromium (III) chloride catalyst formulation (0.06 percent of the reactant mixture) was added and the.temperature was raised to 115°C. The mixture was tested to determine the amount of free acid present.

At 1 to 1.2 percent acid, oxalic acid (0.02 percent of 09A the reactant mixture) and styrene (15 percent of the reactant mixture) were added. The product temperature was reduced below 90°C and 400 ppm phenothiazine (0.03 percent of the reactant mixture) and styrene percent of the reactant mixture) were added.

Castings were prepared by curing a. described in Example 1. The sample was designated as Sample No. 11.

In a similar manner, castings of a vinyl ester resin product containing 35 percent styrene were prepared therein. This sample was designated as Sample No. 12.

For comparison purposes were prepared vinyl ester resin products containing 30 arid 35 percent styrene polymerized therein, but prepared from the epoxy resin and not from the rubber-modified epoxy resin. These samples were designated as Sample Nos. C- 11 and C-12, respectively.

32,619-F -34r Data concerning the physical properties of the various samples are presented in Table V.

154 32,619-F a

C

TABLE V SapePercent~ 1) SampleRubber 9 .00 8.36 Tensile (2) (psi) (MPa) 6,834(47) 6,929(48) 61229(43) 7,998(55) Tensile(3) Percent( 4 Flexural(5) Flexural( 6 Modulus_ Elongation (psi)(MPa) Modulus_ HDT (7) GjC(8) (KJ /m) C-i 1* C-12* 3.37(2323) 3.36(2317) 4.72(32514) 4-95(3'413) 2.99 3.21 1.62 1.79 14,196(98) 4.22(2910) 149353(99) 4.37(3013) 17,649(122) 5.914(41096) 18,434(027) 5,9504102) 276 297 302 310 0.15 0.17 0.09 0.07 Not an exampl?,?f the inv~q ion.

For Footnotes through see correbponding Footnotes at Table I.

8 )Surface fracture energy values (G-jC) are measured -using a compact tension testing method as described by C. Y. C Lee and W. B. Jones, Jr. in Poly, Enk. Sci., Vol. 22, p. 1190 (1982).

I

V -37- The data in Table V indicate that the sample of~ this tnvention exhibits improved elonga, -n and surface fracture energy over an unmodified mat 32,619-F -7 -37-

Claims (7)

1. A dispersion which comprises an uncured vinylized epoxy resin prepared from an uncured epoxy resin as a continuous phase having dispersed therein an insoluble polymer and (ii) a dispersion stabilizer which is the polymer- izate of at least one vinyl monomer and a vinylized epoxy resin adduct derived from the reaction product of an unsaturated carboxylic acid, an unsaturated isocyanate or an alkenyl substituted phenol and a polyepoxide, said insoluble polymer having been polymerized in situ in the uncured epoxy resin and in the presence of the dispersion stabilizer, and the uncured epoxy resin subsequently vinylized by reacting the uncured epoxy resin with an ethylenically unsaturated acid; the o insoluble polymer dispersed phase further characterized in that it forms an insoluble polymer dispersion in the uncured epoxy o o' and remains a stable dispersion in the vinylized epoxy resin at a v, a temperature above 60 0 C.

2. The dispersion of vinylized epoxy resin of claim 1 wherein said in situ polymerized polymer is a polymerizate of at least one ethylenically unsaturated monomer. rI -39-

3. The dis.persion of vinylized epoxy resin of Claim 1 which is a vinyl ester resin.

4. The dispersion of vinylized epoxy resin of Claim 2 wherein said in sjtu polymerized polymer is polymerizate of an alkyl ester of acrylic acid or methaorylio acid. The dispersion of vinylized epoxy resin of Claim 1 wherein said epoxy resin is a polyepoxide,

6. The dispersirn of vinyLized epoxy resin of Claim 5 wherein said polyepoxide is a halogenated S ipolyepoxide. p 15 7. The dispersion of vinylied epoxy resin of tit. Claim 5 wherein said polyepoxide is an epoxy novolac. rr8. The dispersion of vinylized epoxy resin of Claim 4I wherein said alkyl group comprises an alkyl group containing greater han 4 carbon atoms.

9. The vinylized epoxy resin of Claim 1 I wherein said unsaturated isocyanate is isocyanatoethyl methacrylate and said polyepoxide is a diglycidyl ether 25 of bisphenol A. The vinylized epoxy resin of Claim P1 wherein said alkenyl phenol is isopropenyl phenol and said polyepoxide is a diglycidyl ether of bisphenol A. PHILLIPS ORMONDI8 FITZ A~trnoyO 32,619- -39- TE 40

11. A dispersion of claim 1 substantially as hereinbefore described with reference to any one of the Examples. DATED: 18 December, 1989 THE DOW CHEMICAL COMPAN~Y By their Patent Attorney: PHILLIPS ORMONDS FITZPATRICK R r w *1 r t rt, 1- I# I t I I I II I I *4*9 9 9, 9 9 4* 1 9 4* I. 9 I I I I II I 111114 9